I can answer some of those questions- the aircraft used tended to be a mix of whatever was on hand. On one extreme, there are accounts of old and helpless training aircraft being loaded up with explosives and sent out against the American fleets. More commonly, Zero fighters, various single-engine attack aircraft, and other contemporary aircraft were simply fitted with the bombs that they were equipped to use conventionally, and crashed into ships.

There were some aircraft that were expressly designed with suicide attacks in mind, most interesting of which was the Yokosuka MXY7. These aircraft, basically ~1200 kg bombs with stubby wings, rudimentary flight controls, and three solid rocket motors. These were carried to the target area by Mitsubishi G4M bombers, released to glide, and then engaged the rockets during the terminal dive to reach very high speeds. The drawback was the fact that the slow, vulnerable bombers needed to get very close before releasing the Ohka aircraft, and there's some fascinating color gun camera footage floating around somewhere of American fighters shooting down bombers with Ohka's strapped to them.

The attacks did see some successes- most notably the attack on the American carrier Bunker Hill off Okinawa in May 1945, and the initial attacks on the American forces at the Battle of Samar in October 1944, sinking the escort carrier St. Lo. However, interestingly enough several of the conventional attacks by the Japanese air forces during this same time period saw successes at well. For example, the escort carrier Princeton was destroyed by a conventionally dropped bomb during the same first attack the St. Lo was lost during, Samar in October 1944, and the fleet carrier USS Franklin was crippled by conventionally dropped bombs in March 1945. Anyways, the Allied navies did see Kamikaze attacks as the most potent threat the Japanese could field against naval forces late in the war, and went to great lengths to protect against them. However, it's difficult to say if measures like picket ships and continuous air coverage wouldn't have happened anyway with conventional attacks. While the attacks did have some successes like the ones mentioned above, they were obviously unsustainable, and can most accurately be seen as a measure of desparation.

At War With the Wind by David Sears is a great book about this exact topic.

First of all, what were the long-term goals for the Kamikaze tactic? Did the Japanese government use old planes and fresh recruits in a last ditch effort to turn the tide of war and maybe get out of the war without losing outright? Or did they aim to use these rather effective (if they managed to hit..) anti-ship tactics to win the war?

By this point in the war, it was evident to all but the most delusional Japanese commanders and politicians that Japan had no chance of winning the war against the United States. The use of Kamikazes and pretty much every other aspect of the Japanese strategy was meant to inflict enough damage on the United States that it would be willing to negotiate a surrender that would be more favorable for the Japanese (i.e. Forcing the Americans to compromise on their demand for "Unconditional Surrender").

In conjunction with that question, how did the Kamikaze doctrine affect the Japanese industrial warmachine? Did it use obsolete and/or older aircraft? Or did they produce specific Kamikaze planes to fulfill this purpose?

By this point in the war, Japan's industrial base had been all but crippled through a combination of bombing raids, submarine warfare, and Operation Starvation, the American naval mining effort, and was simply unable to produce even a fraction of the aircraft it had been able to in the pre-war years. When Kamikazes first appeared, they were often times no more than converted fighters or dive-bombers modified to the point that they were essentially manned missiles. However, by the end of the war, you had models such as the Ki-115 that were designed as cheap aircraft meant to serve as Kamikazes.

Thirdly, how effective were Kamikaze attacks? What were some big flaws? Is there a chance we will se more of these in the future?

In terms of effectiveness, the kamikazes were only rerlativel succesful throughout the war. According to a US Air Force study:

Approximately 2,800 Kamikaze attackers sunk 34 Navy ships, damaged 368 others, killed 4,900 sailors, and wounded over 4,800. Despite radar detection and cuing, airborne interception, attrition, and massive anti-aircraft barrages, 14 percent of Kamikazes survived to score a hit on a ship; nearly 8.5 percent of all ships hit by Kamikazes sank. (Link)

In terms of causing destruction, there is no doubt that the Kamikazes succeeded i this regard. However, they failed in causing enough destruction to make any noticeable difference in the war's outcome, as the formidable US navy was able to easily shrug off these losses and continue on in any given campaign.

However, it is important to realize that despite their inability to make the difference that Japanese commanders hoped for, by this point in the war, there were very few alternative viable strategies for Japanese aviators. By 1944, not only had the IJN lost nearly all of its experienced pilots, but the aerial superiority its fighters had enjoyed early on the war was gone, as they now found their planes to be obsolete in comparison to their American counterparts, and worse still, they often found themselves short on fuel. The US meanwhile enjoyed superiority in quantity of planes, and the the quality of the pilots and the aircraft themselves. Not only that, but the growing naval dominance of the US meant that Japanese aircraft would very rarely make it through to their targets (Carriers, Battleships, etc.) without facing heavy flak from picket forces patrolling the seas (this would be why a great deal of the damage done by Kamikazes was inflicted on destroyers and other light escorts). The US simply outclassed the Japanese in every way by this point of the war, and Kamikazes, while obviously not ideal, were the best way the Japanese could use their inexperienced and obsolete air force.

For further reading, check out John Costello's "The Pacific War 1941-1945"